tonight this video which caused a national debate about the use of force, a police officer firing on a car, a mother, her mini van filled with children, tonight the policeman tells us what he was thinking, abc's ryan owens has the exexclusive interview. Reporter: It's a terrific stop that outraged people. A mom stopped for speeding along a new mexico highway keeps taking off on the police with her five children in the minivan. Open the door! Open the door! Reporter: At that point, two more officers show up for backup. One of them, elias montoya, fires three shots as the minivan takes off again. Watch as he lines up with the white line on the road and appears to aim at the left rear. I'm shooting at a tire. Reporter: Those gunshots cost him his job, montoya says the dark tint on the van's window prevented him from seeing the children, ages 6 to 16. When you found out that there were in fact children in that minivan, what did you think? My heart sank when they finally stopped. I couldn't believe it that there were that many children in there. Reporter: The 53-year-old father of three says he never would have pulled the trigger if he knew that. Still, state police fired him last month for violating their use of deadly force policy. The driver, 39-year-old orlana ferrell, is awaiting trail on charges of child abuse and fleeing police. She's pleaded not guilty. Montoya just wants his job back. But, can the public trust your judgment after you fired on a minivan with kids in it? I'm sure they will because they know me. They know what I am about. Reporter: Ryan owens, abc news, taos, new mexico.

This transcript has been automatically generated and may not be 100% accurate.

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